Transmission control circuit for use in TDMA communication devices

Abstract

A transmission control circuit for use in a TDMA communication device controls the rise and fall characteristics of driving voltages applied to high-frequency amplifier circuits in such a way that the generation of unnecessary waves at the time of transmission can be restrained to a minimum, wherein a driving voltage ON/OFF circuit B1 outputs first and second driving voltages S1 and S2 having different rise and fall time constants, the first driving voltage S1 being supplied to a first high-frequency amplifier circuit A1, and the second driving voltage S2 to a second high-frequency amplifier circuit. The requisite rise time for the driving voltage S1, which is supplied to the first high-frequency amplifier circuit A1, is longer than the requisite rise time for the ON/OFF switching signal S2, supplied to the second high-frequency amplifier circuit A2, and the requisite fall time for the driving voltage S1 is shorter than the requisite fall time for the second ON/OFF switching signal S2, which is supplied to the second high-frequency amplifier circuit A2.

What is claimed is: 
     
       1. A transmission control circuit for use in a TDMA communication device, comprising: a first high-frequency amplifier circuit for amplifying a modulated wave;   a second high-frequency amplifier circuit for amplifying an output of said first high-frequency amplifier circuit; and   a driving voltage ON/OFF circuit for generating first and second driving voltages on the basis of an input ON/OFF switching signal, said first driving voltage being supplied to said first high-frequency amplifier circuit and said second driving voltage being supplied to said second high-frequency amplifier circuit,   wherein said first driving voltage includes a requisite rise time which is longer than a requisite rise time of said second driving voltage and the first driving voltage includes a requisite fall time which is shorter than a requisite fall time of said second driving voltage.   
     
     
       2. A transmission control circuit for use in a TDMA communication device according to claim 1, wherein said driving voltage ON/OFF circuit includes: a first transistor of the PNP type to the base electrode of which said ON/OFF switching signal is applied, to the emitter electrode of which a power source voltage is applied, and the collector electrode of which is grounded in series through a first resistor and a first capacitor; and   a second transistor of the NPN type to the base electrode of which said ON/OFF switching signal is applied, the collector electrode of which is connected through a second resistor to a node between said first resistor and said first capacitor, and the emitter electrode of which is grounded.   
     
     
       3. A transmission control circuit for use in a TDMA communication device according to claim 2, wherein said second high-frequency amplifier circuit has a non-linear amplification characteristic. 
     
     
       4. A transmission control circuit for use in a TDMA communication device according to claim 1, wherein said second high-frequency amplifier circuit has a non-linear amplification characteristic.